(a - 19.99) : 2 = 1 x 1 + 1 x 2 + 1 x 3 + 1 x 4 +...+ 9 x 7 + 9 x 8 + 9 x 9
(a - 19.99) : 2 = 1 x (1 + 2 + 3 + 4 + 5 + 6 + 7 )
Á Xl, mình ấn nhầm nhé '-' Câu trl k đúng đâu !!
xong chưa????????????????
(1/1x2+1/1x3+1/1x4+1/4x5+...+1/127x128):a=1/2+1/3+1/4+1/5+1/128
Giúp mình với
Các bạn giúp mình với :
Tính bằng cách thuận tiện nhất
a) A = 20,15 x 25,75 + 74,25 x 20,15
b) B = \(\frac{2}{1x3}+\frac{2}{3x5}+\frac{2}{5x7}+\frac{2}{7x9}+\frac{2}{9x7}\)
a=1/1x2 + 1/2x3+ 1/3x4 +...1/99x100
b=4/1x3+4/3x5+4/5x7 +...+4/51x53
Tính
A=1x2x3+2x3x3+3x4x3+4x5x3+....+98x99x3
B=1x2+2x3+3x4+4x5+...+98x99
C=1x1+2x2+3x3+4x4+5x5+...+98x98
a] A=1x2 +2x3+3x4+...+ 99x100
b]B=1x100+2x99+3x98+99x2+100x1
c] C=1x1+2x2+3x3+...+100x100
tinh tong 99x100+100x101+............+199x200
1x3+3x5+5x7+.............+99x101
21x23+23x25+25x27+.............+111x113
1x4+4x7+7x10+.............+100x103
1x5+5x9+9x13+ .......................+101x105
bài 1:tìm X
phần a, 1/1x2 + 1/ 2x 3 + 1/ 3 x4 + ....+ 1/ X x( X +1)= 499 / 500
phần b,1/1x3 + 1/3x5 + 1/ 5 x 7+ ....+ 1/X x ( X + 2 )= 20 /41
1.Tính giá trị biểu thức
a,2+4+8+16+...+1024
b,1x2+2x3+3x+4x5+... + 14x15
2.Tìm x
a, ( 1+x) + ( 2+x) + ( 4+x) + ( 7+x)+...+(22+x) = 77
b,X + 2 x X+3 x X+4 x+ ... + 100 x X = 15150
c,X x X + 1x1+2x2 + 3x3 + 4x4 + ... +20x20 = 2895
a)A=1+2+3+4+......+0
b)B=1/1x2 + 1/2x3 + 1/3x4 +.....+1/99x100
c)C=1 + 1/3 + 1/6 =1/10+.....+1/120
d)D=1/1x4 + 1/1x7 1/7 x 10+.....+1/97x106
e)1/2 x (1+2) + 1/3 x (1+2+3) + 1/4 x(1+2+3+4) +......+1/16 x (1+2+...+16)
